Airbag devices and seat-belt devices are known as an occupant protection system configured to protect an occupant seated on a seat upon input of an impact load. These airbag devices and seatbelt devices are ones for regulating the movement of the upper body of an occupant upon input of an impact load; at this time, it is particularly crucial to stably restrict the movement of a head part and a neck part of the occupant. Thus, various occupant restraint systems for dealing with this have been devised (see Japanese Patent Application Publication No. 2015-51744, for example).
The occupant restraint system described in Japanese Patent Application Publication No. 2015-51744 has a bag body of an airbag device that is embedded in a lap belt part of a seatbelt device designed to restrain a waist part of an occupant, and is designed so that the bag body expands and deploys from the lap belt part upon input of an impact load. In addition, the bag body includes: a lower bag part for restraining a chest part and an abdominal part; and an upper bag part, for restraining a head part. After the lower bag part expands and deploys, the upper bag part deploys and restrains the movement of the head part of the occupant.
The existing occupant restraint system described above can restrict the forward movement of the head part of the occupant upon input of an impact load by the expansion and deployment of the upper bag part; however, it is hard for the upper bag part to directly contact with the neck part of the occupant upon input of the impact load. Hence, it has been demanded to restrain the neck part of the occupant stably.